Thursday’s Highlights: 'The Big Bang Theory'; 'Community'

The Big Bang Theory: Wolowitz (Simon Helberg) is making his final preparations for the NASA mission in the season finale. Jim Parsons, Johnny Galecki, Kaley Cuoco and Mayim Bialik also star (8 p.m. CBS).Community: Abed (Danny Pudi) starts believing there’s a conspiracy and Dean Pelton (Jim Rash) is an impostor, but when he’s caught sneaking around campus, he’s ordered to seek professional help or go to jail. John Hodgman guest stars as his therapist in this new episode (8 p.m. NBC).The Vampire Diaries: Jeremy (Steven R. McQueen) makes a big decision aimed at protecting Elena (Nina Dobrev) in the season finale (8 p.m. KTLA).American Idol: Jennifer Lopez performs and David Cook performs in this results episode (8 p.m. Fox).The Office: The theft of a diaper leads to a high-speed car chase in the season finale (9 p.m. NBC).The Secret Circle: Jake, Melissa and Adam try to save Faye from the witch hunters in the season finale (9 p.m. KTLA).Grey’s Anatomy: The residents make their choices about where to work next in the season finale (9 p.m. ABC).Parks and Recreation: It’s Election Day, and the race between Leslie and Bobby (Amy Poehler, Paul Rudd) is too close to call in the season finale (9:30 p.m. NBC).